An ink jet printer cartridge is known which includes a memory device in the form of chip or EEPROM. The chip stores data which, amongst other things, relates to the ink level of the cartridge and the date of manufacture of the cartridge. When the cartridge is installed in the appropriate printer, the chip is read by the printer. If the data representing the date of manufacture indicates that the cartridge is beyond a certain age, then the printer will warn the user, or simply will not work. Similarly, if the data presenting the ink level of the cartridge indicates that the cartridge has too low a level of ink to be used then the printer will not work and an explanatory signal may be given to the user. The printer for the cartridge continually writes to an internal memory as it prints to update data held therein representing the ink level. Once the data indicates that the ink level in the cartridge is below a predetermined threshold, then the pointer will not work until the old cartridge has been removed and a new cartridge has been inserted. The spent cartridge cannot be simply removed from then replaced in the printer, as when the spent cartridge is removed from the printer, the data on ink level from the internal memory of the printer is input to the chip on the spent cartridge. Thus, if the spent cartridge is replaced in the printer, or indeed if it is inserted into a different printer, the chip will be read by the printer, the printer will recognize that the cartridge is empty, and will consequently refuse to draw ink from it.
When a cartridge of this type is empty, it can be refilled in the usual way, but the cartridge still will not be accepted by the printer, because the chip will indicate to the printer that the cartridge is empty.